While the present invention can be effectively used in a plurality of suitable paper or sheet-handling systems, it will be described for clarity as used in electrostatic marking systems such as electrophotography. In an electrostatographic reproducing apparatus commonly used today, a photoconductive insulating member may be charged to a negative potential and thereafter exposed to a light image of an original document to be reproduced. The exposure discharges the photoconductive insulating surface in exposed or background areas and creates an electrostatic latent image on the member which corresponds to the image areas contained within the original document. Subsequently, the electrostatic latent image on the photoconductive insulating surface is made visible by developing the image with a developing powder referred to in the art as toner. During development, the toner particles are attracted from the carrier particles by the charge pattern of the image areas on the photoconductive insulating area to form a powder image on the photoconductive insulating area. This image may be subsequently transferred or marked onto a support surface such as a copy paper (from a feeding station) to which it may be permanently affixed by heating or by the application of pressure.
As above noted, there are many systems that feed or transport paper or other sheet media to the system before the media is marked or treated. These marking systems could include electrostatic marking systems, non-electrostatic marking systems and printers or any other system where paper or other flexible sheet media or receiving sheets are fed or transported internally to a print engine for marking. The present invention can be used as a stacker before a print engine or before entering a finishing station.
The feeder stacker tray assembly in these marking systems usually comprise a stacker tray, controller sensors and height stack switches. Sheet stacker assemblies are well known in the art such as those disclosed in Xerox Corporation U.S. Pat. Nos. 5,188,353; 5,261,655; 5,409,202; 5,476,256; 5,570,172; 5,842,695; 6,443,450 and 6,575,461. The disclosures of these Xerox Corporation patents are incorporated by reference into this disclosure.
Large format media and paper stack featuring ID cards attached to the main sheet are difficult to load into paper trays in substantial quantities due to build up in the area where the cards are attached. If the location of the cards is not near an edge and is located where standard tiltatron design will not work, the paper stack cannot be easily used. Therefore, cards embossed on paper such as ID cards create an uneven stack due to the thickness of the paper containing the ID card and maintaining a flat upper stack surface needed for proper feeding of the paper. Papers with embossed cards are referred to at Xerox Corporation as DocuCards (a trademark of Xerox Corporation). The term “DocuCards” as used in this disclosure refers to all size paper with embossed cards on their surface.